namespace URI name conventions?

Has anyone ever noticed any common patterns in namespace URIs to show that a
URI does represent a namespace? For example, Simon St. Laurent has namespace
URIs following the format http://www.simonstl.com/ns/foo,
http://www.simonstl.com/ns/bar, etc., and I asked him if there was any
precedent for the /ns/ part, and he said no. 

Assuming that we don't want to hang them off the root directory (e.g.
http://www.snee.com/foo) the two obvious choices are a directory name to
identify namespaces as Simon did or a subdomain (e.g.
http://mynamespaces.snee.com/foo or http://ns.snee.com/foo or whatever.)

Has anyone seen any conventions repeated often enough to qualify as
conventions?

thanks,

Bob DuCharme          www.snee.com/bob           <bob@  
snee.com>  "The elements be kind to thee, and make thy
spirits all of comfort!" Anthony and Cleopatra, III ii